The preparation of .beta.-glucuronides has been carried out by a number of different techniques. Chemical synthesis typically involves condensation of a suitably protected aglycon with an alkyl (2,3,4-tri-O-acetyl-.beta.-D-glucopyranosyl halide) glucuronate followed by deprotection of the glucuronide and aglycon (Ando, K., Suzuki, S., and Arita, M. [1970] J. Antibiotics 23, 408; Sarett, L. H., Strachan, R. G., and Hirschmass, R. F. [1966] U.S. Pat. No. 3,240,777). A second approach involves feeding large amounts of the aglycon to animals, collecting their urine and isolating the glucuronide (Hornke, I., Fehlhaber, H. W., Uihlein, M. [1979] U.S. Pat. No. 4,153,697). Alternatively, the animal can be sacrificed and the bile isolated from its gall bladder from which the glucuronide is purified (DeLuca, H. F., Schnoes, H. K., and LeVan, L. W. [1981] U.S. Pat. No. 4,292,250). This in vivo synthesis is catalyzed by the class of enzymes known as uridine diphosphoglucuronyl transferases. In vitro use of this enzyme to produce various .beta.-glucuronides has been reported; for example, a phenolic compound has been glucuronidated (Johnson, D. B., Swanson, M. J., Barker, C. W., Fanska, C. B., and Murrill, E. E. [1979] Prep. Biochem. 9, 391).